Joint compensation of power amplifier nonlinearity and I/Q impairments for broadband and dual-band transmitters

In this paper, joint compensation of power amplifier (PA) nonlinearity and in-phase/quadrature (I/Q) impairments algorithms have been proposed. The image interference caused by I/Q imbalance can destroy the orthogonality of the sub-carrier of the transmitting system, resulting in the decrease of the performance. A single step joint correction algorithm is proposed for the broadband amplifier system. For the dual-band amplifier system, I/Q imbalanced compensation model is proposed based on the two-dimensional digital predistortion (2D-DPD) structure of single up-conversion unit. In the experimental, a 30W Class F PA and a 40W GaN Doherty PA were used as the test amplifiers. The input signals are 60-MHz 3-carrier orthogonal frequency division multi-plexing (OFDM) signal and a dual-band signal which is composed of a 5 MHz wideband code division multiple access (WCDMA) signal and a 5 MHz long-term evolution (LTE) signal respectively. The experimental results verify the effectiveness of the proposed methods.